Process for making moldable bagasse compositions

ABSTRACT

PROCESS FOR MAKING FROM BY-PRODCT SUGAR CANE BAGASSE A PLASTIC MASS WHICH CAN BE MOLDED INTO BUILDING WALLBOARD COMPRISING TREATING GROUND BAGASSES WITH SALTS TO CONVERT RESIDUAL SUGAR JUICES TO INERT COMPOUNDS, AND MIXING THE THUS TREATED BAGASSE WITH FROM 10-15% BY WEIGHT OF PORTLAND CEMENT WHICH FILLS THE VASCULAE OF THE BAGASSE STALKS AND BINDS THE FIBERS THEREOF INTO A UNITARY MASS. WALL BOARD MOLDED FROM THE MASS IS LIGHT, STRONG, WATER- AND FIREPROOF AND WILL ADHERE TO CONVENTIONAL BUILDING COATINGS SUCH AS PLASTER, PAINT, MORTAR, PLASTIC OR PAPER SHEETS.

toe-99.

3,748,160 PROCESS FOR MAKING MOLDABLE BAGASSE COMPOSITIONS Manuel Carhajal, Entre Rios 54, Tucuman, Argentina No Drawing. Filed Apr. 13, 1971, Ser. No. 133,752 Claims priority, applicatzioiaalrgentina, June 9, 1970,

Int. Cl. 604]; 7/02 US. Cl. 106-99 Claims ABSTRACT OF THE DISCLOSURE The present invention refers to a process for manufacturing a plastic composition of the type specially suitable for use in the building industry and others, and more particularly, for making panels and wall boards from byproduct sugar cane bagasse as the basic component of said composition.

The process of the invention uses a by-product of an industrial process, which is very cheap and abundant, eliminating the deficiencies of its non-uniform structure and obtaining, as result of same, a homogeneous, fireresistant and water-tight material capable of being shaped to receive and maintain different forms and at the same time be substantially inert.

Sugar cane bagasse constituting the basic material of the board is a fibrous vegetable material having the structure and texture of the sugar cane resulting from extraction of sugar juice by simple mechanical extraction, with or without liquid extraction.

When discharged from the sugar mills, the sugar cane bagasse possesses the following approximate chemical composition, obtained from averageing the results of various analyses:

Traces of wax.

Predominately xylose units joined to metoxyuronic acid.

' The structure of this material is highly fibrous, rough, coarse, rigid and hard, formed of irregular pieces of filaments solidly united, the density of which increases toward the periphery of the stem which is dense, even hard, shiny and watertight. Toward the axis the structure loses density and homogeneity and becomes more spongy until upon reaching the medulla the fibers and filaments disappear altogether.

Resulting from analysis and inspection, the material, in dry state, is composed of equal parts of fibrous filaments and vascular members, the latter being hollow tubes which originally housed the sucrose juice.

The vascular members will retain that part of the sucrose juice which cannot be economically extracted in the sugar processing plant, amounting to about 10% by weight of the total product. This represents from l-1Vz% of sucrose as shown in the above analysis.

Furthermore, the vascular members are those that up "ice to the present have constituted an obstacle to the practical use of this by-product of the sugar industry, the volume of which and its disposition was a constant source of trouble. For example, in the paper industry its disposition consumes a great part of the chemical agents used in liberating fibers and bleaching, besides interfering with the mechanical and beating steps of the process. In the agglomerating industry, its elimination is very costly or else it ends by confiscating enormous quantities of binder which, besides elevating significantly the density of the product, makes its production uneconomical.

Cane bagasse, before destroying its biological economy through comminution and crushing, has a very hard,

flexible, chemically-resistant stem. The vasculae within serve as elastic hermetic, hydrostatic chambers. When these chambers are destroyed, the liquid contained in same is supplanted by free air.

The most economical solution to the problem presented, is that of filling the empty space of the vasculae with a material which provides rigidity, namely portland cement, and fixing on their walls the 10% or so of the sucrose juice which is not extracted in the sugar recovery process. The sucrose is converted to an insoluble and stable compound, thus obviating both obstacles: firstly, insolubilizing free sucrose which interferes or retards the forming of the agglomerate composition; and secondly, providing rigidity to the vascular walls to provide an insoluble body with the sucrose compound of the sucrose juice uniformly diffused in all its structure. Another important obstacle also eliminated is that of the possibility of fermentation during the settling and deposit of the product, which may result in fire due to spontaneous combustion.

The walls of the cellular structure, as shown in the analysis, are made up of reactive complex cellular chemical compounds including saccharides which react with treating salts to render them inert thus avoiding their ulterior interference in the forming of agglomerates in which the portland cement acts as an adherent or hinder.

The product panels obtained by this process molded from the plastic mass containing portland cement are characterized by adequate rigidity and mechanical strength resulting in self-support without additional reinforcement and which at the same time are light, highly insulating, fireand waterproof, permeable to gasses and steam and able to be secured in usual manner and plastered with materials currently used in construction: concrete, mortar, plaster, paints, plastics sheets or papers.

Panels of the type mentioned, 0.07 meter in thickness and around 2.40 meters in height, can support loads of around 7,000 kilograms per linear meter without showing any buckling.

As the adding of portland cement as binder is in proportion of about 15% by weight, and the principal material, as stated, is the sugar cane bagasse, a waste product, the economy of the product is evident.

For a better understanding of the objects of this invention, I will describe, as a non-limiting example, a preferred procedure for practicing the invention.

The sugar cane bagasse resulting from the manufacture of sugar is submitted to a pre-treatment and storage because it is well known that bagasse is produced only during the three-month period when the sugar crop is harvested and ground, while the stabilized product of the invention is manufactured during the whole year.

The pre'treatment is economically effected by conveying the spent bagasse on a belt from the sugar mill to the board processing plant. Iheha sse is treated wi a layer of hot lime while agitated with s earn 0 convert the sucrose juices present to tricalcium saccharinates. The quantity of lime used is determined by frequent laboratory analysis of bagasse, the composition of which is changeable. The bagasse thus treated is drjg d to approximately 25% moisture, then baled, and piled up in storage.

The board-manufacturing process comprises the primary step of comminuting or pounding the pretreated bagasse in an apparatus equipped with stirrers of the hydropulper" type to which odium or ot solJLtipn (6-8 Baum) has been added to form a slurry. The rrTass is then separated from the solution and the solution is recovered for recycling. This step is eflFected within 8 to minutes.

The material obtained in the first step is then subjected to further compounding in an apparatus similar to the one described, in the presence of a 2 to 3% solution of W with a subsequent ehy ration of the mass. The time employed in this step is around 4 minutes.

The mass then is submitted to agitation in an enclosed chamber, in an atmosphere saturated with Imosjlicic acid for a period of about 2 minutes.

The material can then be mixed with portland cement in common mixing equipment, the proportion of cement being not less than 10% by weight, and preferably to form a plastic mass. The mass may be molded to any desired shape under pressures of from 1 to 10 lrg/cm. to obtain specific gravities ranging about 0.680 to 1.100 depending upon the quantity of cement present, which in turn is dictated by the character and nature of the desired product and its practical use.

As already stated, such masses obtained with the addition of portland cement as binder are capable of use in diverse forms and specially apt for panels or wall partitions with thicknesses of up to 0.12 meter.

A substantial reduction in the amount of portland cement in the mass provides a molded product having good insulating properties specially suitable for cold storage rooms and the like.

When carrying out the present invention modifications may be introduced in certain details without departing from the fundamental principles of the invention which are clearly specified in the following claims.

What is claimed is:

1. A process for manufacturing a plastic material from by-product sugar cane bagasse which comprises (a) pretreating said bagasse with hit lime to convert sucrose juices in said bagasse to tricalcium saccharates (b) adding alkali silicate solution to said pretreated bagasse and agitating the slurry thus formed,

(c) removing the bagasse solids from said silicate solution,

(d) adding a solution of calcium chloride to said bagasse solids, agitating the slurry thus formed, and subsequently dehydrating the mass;

(e) subjecting the bagasses mass to an atmosphere of hydrofiuosilicic acid while agitating said solids,

(f) adding portland cement to said solids to form a plastic moldable mass wherein said portland cement is in excess of 10% by weight of said mass.

2. The process of claim 1 in which step (a) is carried out in the presence of steam and said pretreated bagasse is dried to less than about 25% moisture.

3. The process of claim 1 in which said alkali silicate solution has a density of 6-8 Baum and is recovered for recycling, and said calcium chloride solution ranges from 2-3% chloride.

4. The process of claim 1 in which said alkali silicate is sodium silicate.

5. The process of claim 1 wherein the portland cement is 1015% of the mass.

References Cited UNITED STATES PATENTS JAMES E. POER, Primary Examiner 8/1966 Bowlin 106-93 Y 

